Herpes simplex virus (HSV) is the most common cause of infectious blindness and viral encephalitis in the Western countries. Primary or recurrent infection can lead to severe disease, yet no licensed vaccine is available. HSV typically initiates infection in the epithelial cells of mucosa and spreads to sensory neurons where the virus establishes latency. Reactivation from latency occurs intermittently, which is a lifelong source for recurrent lesions. Although viral replication in the mucosa or penetration into the nervous system inflicts damages or inflammation, the disease mechanism is less clear. As a large DNA virus, HSV evokes antiviral responses through the innate immune pathways that regulate TANK-binding kinase 1, a key factor required to activate cytokine expression and autophagy in mammalian cells. Remarkably, while the interferon- stimulated gene (STING) drives the cytokine response the tripartite motif protein 23 (TRIM23) serves to mediate autophagy. Despite such regulatory control, HSV is able to compromise host restrictions, which depends on an HSV virulence factor ?134.5. A central hypothesis of this proposal is that HSV differentially reprograms host immunity, where a dynamic interplay between viral and cellular factors may determine HSV spread, virulence and inflammation. Current effort is directed to decipher mechanisms of HSV pathogenesis. Several aspects of HSV infection will be investigated in a multi- faceted approach. Accordingly, recombinant HSV will be generated to determine the nature of HSV interactions with the innate immune factors in epithelial and neuronal cells. This will dissect elements pertinent to viral interference of the nucleic acid sensing complexes and autophagy machineries. Furthermore, genetic studies will explore viral features relevant to ocular replication, spread and neurovirulence. In parallel, gene expression analysis will assesses ocular and neuoinflammation. Collectively, these studies will provide an insight into genetic determinants of HSV virulence, which may inform design of novel antiviral therapeutics or vaccines.